Electric safety switch



Dec. 8, 1931.

H. J HAMMERLY ELECTRIC SAFETY SWITCH Filed May 14. 1929 Fig. 1.

2 Sheets-Sheet 1 H. J. HAMMERLY ELECTRIC SAFETY SWITCH Filed May 14. 1929 2 Sheets-Sheet 2 Patented Dec. 8, 1931 UNITED STATES PATENT OFFICE BULL ELECTRIC MANUFACTURING COMPANY,

CORPORATION OF CONNECTICUT OF PLAINVILLE, CONNECTICUT, A.

FZI'JI'IGIIB'IC SAFETY SWITCH.

Application filed Kay 14,

My invention relates particularly to whatare generally termed .enclosed switches of the meter testing type, although certain features may be applicable to other constructions as will be seen from the following specification.

One object is to provide a simple and convenient switching means for making meter testing connections without interrupting the regular load circuit.

Another object is to provide means for cutting out the meter for testing purposes and for insuring the return of the testin switch to its normal running condition a ter the testing is completed.

Another object is to provide a simple and effective type of fused-switch in which the movable switch member also carries the fuse.

Another object is to provide a double break switch construction with means for preventing arcing of the contacts.

Another object is to provide a switch of this type in which the movable. contacts and fuse terminals are entirely disconnected from the circuit when the switch is open, thus enabling the ins ector to remove and insert fuses without anger.

Fi 1 is a front view of the switch embodying one form of the improvement of my invention, the cover of the box being open I and broken away.

Fig. 2 is a transverse sectional view of the box showing the switch mechanism in end elevation. This also shows the handle of one of the meter testing switches in position to block the closing of the cover. 1

Fig. 3 is a longitudinal view and side elevation showing the switch in the open circuit position and the box closed.

Fig. 4 is a fragmentary, transverse, sectional view showing the main switch in the open circuit position and the meter testing switch in the closed circuit position.

Fig, 5 is a detailed sectional view of one of the movable blade and fuse carriers.

The box 10 may be of any suitable construction and preferably provided with a hinged cover 11 and a spring catch or latch 12, as is customary.

i929. Serial No. 863,002.

The insulating base 13 is suitably secured in the box and carries the circuit terminals and switch parts. The operating crank 14 is pivotally supported by the opposite side walls of the box and passes underneaththe base. This crank has an external operating handle 15. The invention is applicable to the control of any number of circuits or poles of a circuit. The particular form illustrated is adapted for a 3-wire meter testing system. The terminal parts 16 and 17 constitute the circuit connections for one side of a circuit and. have connected to them stationary spring contacts '18 and 19 respectively. Between these contacts is mounted an insulating connector 20 which extends through the base and is connected at the rear with the operating crankl l.

On the other end'of the connector is an insulating cross bar 21, which carries fuse clips 22 and 23 which are adapted to re- .ceive a cartridge type fuse 24. Contact date either the spring clips for the cartridge type fuse, as above described, or the screw shell 27 and center contact 28, shown in Fig. 5, for a screw plug type fuse. In this case the contact blade 29 is electrically connected with the base of the screw shell 27 and the contact 30 is electrically connected with the center contact screw 28. v

To close the circuit it is simply necessary to move the handle 15 upwardly so that the crank 14 pulls the connector 20 downwardly and carries the switch blades 25 and 26 into frictional engagement with the stationary spring contacts 18 and19 respectively. The circuit is opened by the movement of the switch handle in the opposite direction. It will be seen that as soon as the blades25 and 26 leave the contacts 18 and 19 the circuit is broken in two places and the solid insulation of the connector 20 remains interposed between the contacts 18 and 19 so as to make arcing between"these contacts practically impossible.

The meter testing switch includes the stationary terminal parts 31 and 32 and to one of these terminals (preferably 31) there is hinged or pivoted a movable auxiliary blade 33 for connecting or disconnecting these terminals. The auxiliary blade 33 normally connects the terminals 31 and 32 butwhen testing the meter the blade is moved to the position shown in full lines in Fig. 1 so as to disconnect terminal 32 and to connect terminal 31 with terminal 32 in which position the meter is disconnected or cut out of the load circuit. A handle 34 is provided for operating the blade 33. The stem of the handle projects freely through a perforation in the blade 33 which perforation is preferably drawn up or cupped at 33 so as to provide sufiicient length of bearing to maintain the handle in a relatively upright position.

In the closed circuit position the inner end of the handle 34 rests in the recess 35 in the base but when the switch member 33 is swung into the open circuit position the handle 34 is pulled or drawn outwardly so that when in position for testing the meter its inner end is in the shallower recess 36. The result is that when the auxiliary blade is in the meter testing position, the handle protrudes so that the cover 11 will strike against the outer'end of the handle and the cover can not be closed, thus warning the inspector that the meter testing switch is not in correct position for including the recording meter in the circuit.

When the meter testing switch is again closed the handle 34 will be in the position shown in Fig. 4 and the cover may then be closed.

It should be understood that various changes may bemade in the construction and arrangement of the parts within the spirit and scope of my invention. 7

I claim:

1.. An electric switch including an insulating base having a channel extending across the back, an operating crank movable in said channel, a pair of mounted on the front of the base, said base having a passage extending therethrough be tween the stationary contacts, an insulating se carrier having a projecting portion for shielding said stationary contacts and mountedto slide in the passage in said base between the stationary contacts and connected to said operating crank in the rear of saidbase andhaving two spaced switch blades mounted thereon for engaging said stationary contacts, and a fuse terminal connected with each of said switch blades on the opf posite side of the connector.

2. 'An electric switch including an'insulatprojecting portion of said to limit stationary contacts ing base having a passage therethrough, two stationary contact members mounted on said base, an insulating member having a projecting portion for shielding said stationary contacts and mounted for limited movement through the passage in said base between said stationary contact members, two contact blades secured to said movable member and adapted to engage said stationary contacts upon movement of the insulating member, two fuse clips mounted on the said projecting portion of said movable member and con nected with the respective blades on the opposite side of said projecting portion, a crank connected to the other end of said insulating member for operating the blades, a portion of said insulating member being adapted to remain interposed between said stationary contact members in all of the operating positions of said insulating member.

3. An electric switch including an insulating base having a guide passage therethrough, a pair of stationary contacts mounted on said base, an insulating connector movable through and guided by said passage between said stationary contacts and having an extended portion for shielding said statlonary contacts, a pair of spaced. blades mounted on opposite sides of said connector for engagement with said stationary contacts, a pair of fuse terminals mounted on the extended portion of said connector and connected with the respective blades and means the movement of said connector whereby a portion of said connector is'interposed between said stationary contacts in all operative positions of said connector.

4. An electric switch including an insulating base having a guide passage therethrough, two stationary contacts mounted on said base, 1 an nsulating connector movable in said guide passage between said stationary contacts, and having an extended head portion, a movable switch blade-on each of the opposite sides of said connector for engagement with said stationary contacts, two fuse terminals mounted on the. extended head portion of said connector and connected with the respective blades, and an operating crank connected' with the other end of said connector, a P01? 115 tion of said insulating connector being adapted to be interposed between said statlonary contacts in all operating positions of said connector.

5. In an electric switch, an insulating base having a passage therethroug a stationary contact mounted on said base at each of the opposite sides of said passage, an insulating carrler of greater width than said contacts and slidable through said passage, and having a pro ecting contact shielding portion, use terminals mounted on the projecting portion of said carrier and switch terminals connected to the fuse terminals on the opposite side of the projecting portion of said 130 carrier and ada ted to engage the stationary contacts when t e carrier is in the closed circ uit position, a portion of said carrier being interposed between the stationary contacts 5 when the switch is in the open circuit position.

HERMAN J. HAMMERLY. 

